This invention relates to improvements in the treatment of gastrointestinal disorders. More particularly it relates to the use of a compound having antagonist activity at 5HT3 receptors and dexamethasone in the treatment of emesis, and to pharmaceutical compositions containing the two compounds.
In our UK Patent Specification No. 2153821A we disclose inter alia 1,2,3,9-tetrahydro-9-methyl-3-[(2methyl-1H-imidazol-1-yl)methyl]-4H-carbazol-4-one which may be represented by the formula (I) 
and physiologically acceptable salts, solvates and physiologically acceptable equivalents thereof.
In the aforementioned specification the compounds are described as potent and selective antagonists of 5- hydroxytryptamine (5HT) at xe2x80x98neuronalxe2x80x99 5HT receptors of the type located on terminals of primary afferent nerves, and which are also present in the central nervous system. Receptors of this type are now designated 5HT3 receptors. The compounds are described as being of use in the treatment of a human or animal subject suffering from a condition caused by a disturbance of neuronal 5HT function, for example in the treatment of migraine pain or a psychotic disorder such as schizophrenia. The compounds may also be useful in the treatment of conditions such as anxiety, obesity and mania.
We have found, as described in our published European Patent Specification No. 226266, that the compounds disclosed in UK Patent Specification No. 2153821A additionally promote gastric emptying, and are thus useful in the treatment of conditions which may be relieved by the promotion of gastric emptying. Such conditions include gastric stasis and symptoms of gastrointestinal dysfunction such as dyspepsia, reflux oesophagitis, peptic ulcer and flatulence.
According to published European Patent Specification No. 226266, the compounds have also been found to be anti-emetics, and may be used in the treatment or prevention of nausea end vomiting. The use of these compounds for the treatment of emesis is also described in published European Patent Specification No. 201165, which specification additionally refers to the use of the compounds for the treatment of irritable bowel syndrome.
Studies have shown that the anti-emetic properties of the compound of formula (I) are enhanced by administering the compound in conjunction with dexamethasone. Dexamethasone is a systemic anti-inflammatory corticosteroid, which is known to have anti-emetic properties and to be useful in the treatment of emesis resulting from chemotherapy, especially cancer chemotherapy involving the use of, for example, cisplatin.
The present invention thus provides a method of treating end/or preventing nausea and vomiting, which comprises administering to a human or animal subject the compound of formula (I) or a physiologically acceptable salt or solvate thereof, end dexamethasone or a physiologically acceptable salt or ester thereof.
According to another aspect the Invention provides for the use of the compound of formula (I) or a physiologically acceptable salt or solvate thereof for the manufacture of a medicament for administration in conjunction with dexamethasone or a physiologically acceptable salt or ester thereof, for the treatment and/or prevention of nausea and vomiting.
Co-administration of the compound of formula (I) with dexamethasone is particularly useful for the treatment end/or prevention of nausea and vomiting associated with chemotherapy, especially cancer chemotherapy involving the use of, for example, cisplatin. Such co-administration may also reduce delayed nausea and vomiting associated with this type of chemotherapy.
The compound of formula (I) or a physiologically acceptable salt or solvate thereof, and dexamethasone or a physiologically acceptable salt or ester thereof, may be administered as a single pharmaceutical composition comprising effective amounts of the two active ingredients. Alternatively the two active ingredients may be co-administered in the form of two separate pharmaceutical compositions for simultaneous or sequential use.
Suitable physiologically acceptable salts of the carbazolone of formula (I) for use according to the invention include acid addition salts formed with organic or inorganic acids for example, hydrochlorides, hydrobromides, sulphates, phosphates, citrates, fumarates and maleates. The solvates may, for example, be hydrates. A preferred form of the compound of formula (I) for use according to the invention is the hydrochloride, particularly in hydrated form, e.g. the dihydrate.
Dexamethasone may be administered according to the invention as dexamethasone alcohol or in the form of a physiologically acceptable salt or ester. Suitable salts and esters include the acetate, isonicotinoate, phenylpropionate, pivalate, t-butyl acetate, trioxaundecanoate, disodium metasulphobenzoate and disodium phosphate.
A proposed dosage of the compound of formula (I) for use according to the invention for administration to man (of approximately 70 kg body weight), is 0.05 to 25 mg, more preferably 0.05 to 20 mg, and most preferably 0.1 to 10 mg per unit dose, expressed as the weight of free base. A preferred dose of dexamethasone for use according to the invention is in the range of 0.5 to 20 mg per dosage unit, expressed as the weight of the alcohol.
The unit doses may be administered, for example, 1 to 4 times per day. The exact dose will depend on the route of administration and the condition being treated, and it will be appreciated that it may be necessary to make routine variations to the dosage depending on the age and weight of the patient as well as the severity of the condition to be treated.
When the two active ingredients are administered as separate preparations, they are preferably given orally or parenterally (e.g. intramuscularly or, more particularly, intravenously).
According to a further aspect the invention provides a pharmaceutical composition, for use in human or veterinary medicine, comprising the compound of formula (I) or a physiologically acceptable salt or solvate thereof, and dexamethasone or a physiologically acceptable salt or ester thereof.
Compositions according to the invention may be formulated in conventional manner using one or more physiologically acceptable carriers or excipients. Thus the compositions may, for example, be formulated for oral, buccal, parenteral or rectal administration. Compositions for administration by the oral route, in the form of for example tablets or capsules, are preferred.
Compositions for oral use such as tablets and capsules may be prepared by conventional means with pharmaceutically acceptable excipients such as binding agents (e.g. pregelatinised maize starch, polyvinylpyrrolidone or hydroxypropyl methylcellulose); fillers (e.g. lactose, microcrystalline cellulose or calcium hydrogen phosphate); lubricants (e.g. magnesium stearate, talc or silica); disintegrants (e.g. potato starch or sodium starch glycollate); or wetting agents (e.g. sodium lauryl sulphate). Tablets may be coated by methods well known in the art. Liquid preparations for oral administration may take the form of, for example, solutions, syrups or suspensions, or they may be presented as a dry product for constitution with water or other suitable vehicle before use. Such liquid preparations may be prepared by conventional means with pharmaceutically acceptable additives such as suspending agents (e.g. sorbitol syrup, cellulose derivatives or hydrogenated edible fats); emulsifying agents e.g. lecithin or acacia); non-aqueous vehicles (e.g. almond oil, oily esters, ethyl alcohol or fractionated vegetable oils); and preservatives (e.g. methyl or propyl-p-hydroxybenzoates or sorbic acid). The preparations may also contain buffer salts, flavouring, colouring and sweetening agents as appropriate.
Preparations for oral administration may be suitably formulated to give controlled release of one or both active ingredients.
For parenteral administration the compositions may be presented in a form suitable for bolus injection or continuous infusion. Formulations for injection may be presented in unit dosage form e.g. in ampoules or in multi-dose containers, with an added preservative. The compositions may take such forms as suspensions, solutions or emulsions in oily or aqueous vehicles, and may contain formulatory agents such as suspending, stabilising and/or dispersing agents. Alternatively, the active ingredients may be in powder form for constitution with a suitable vehicle, e.g. sterile pyrogen-free water, before use.
For rectal administration the compositions may be formulated as suppositories or retention enemas, e.g. containing conventional suppository bases such as cocoa butter or other glycerides.
The pharmaceutical compositions of the invention may be prepared according to conventional techniques well known in the pharmaceutical industry. Thus, for example, the compound of formula (I) or a salt or solvate thereof and the dexamethasone or dexamethasone salt or ester may be admixed together, if desired, with suitable excipients. Tablets may be prepared, for example, by direct compression of such a mixture. Capsules may be prepared by filling the blend along with suitable excipients into gelatin capsules, using a suitable filling machine. Controlled release forms for oral or rectal administration may be formulated in a conventional manner associated with controlled release forms.
The compositions for use according to the invention may, if desired, be presented in a pack or dispenser device which may contain one or more unit dosage forms containing the active ingredients. The pack may for example comprise metal or plastic foil, such as a blister pack. The pack or dispenser device may be accompanied by instructions for administration. Where the compound of formula (I) and the dexamethasone are intended for administration as two separate compositions these may be presented in the form of, for example, a twin pack.
The following examples illustrate the preparation of the compound of formula (I). Temperatures are in 0C.